Preparation of beta-lactones



Patented Sept. 28, 1948 UNITED STATES PATENT OFFICE 2,450,132PREPARATION OEfi-LACTONES Hugh J. Hagemeyer, Jr., Kingsport, Tenn., as-

signor to Eastman Kodak Company, Rochester, N. Y., a corporation of NewJersey No Drawing. Application Juiy 12, 1947,

, Serial No. 760,699

22 Claims. (Cl. 260-344) tones to give lactones (Annalen 384, 1911,pages 38 to 135, and Annalen 380, 1911, page 243) and with unsaturatedketones to give unsaturated hydrocarbons (Annalen 401, 1913, page 263).It has long been known that aldoketenes, such as methyl ketene, readilypolymerize to the dimer under ordinary conditions of temperature andpressure. Boese in U. 8. Patent No. 2,108,427, dated February 15, 1939,shows that ketene dimers react with aldehydes to produce unsaturatedketones, The

process of my invention, however, is applicable both to aldoandketo-ketenes although ketene itself is usually preferred.

Kung in U. S. Patent No. 2,358,459, dated August 22, 1944, shows thereaction between ketenes and aldehydes and ketones to producebeta-lactones, a catalyst of the Friedal-Crafts type being employed. Ithas now been found that ketenes react with di-ketones in the presence ofP-riedel-Crafts type catalysts, as well as their organic complexes suchas etherates, etc., to produce the beta-lactones of my invention.

An object of my invention is to provide a process for preparing lactonesof keto. beta-hydroxy carboxylic acids and beta,beta-dihydroxy-dicarboxylic acids.

Other objects will become apparent from a consideration of the followingexamples.

Accordingly, my new beta lactones are prepared by passing'a ketene intoa solution containing the diketone and a Friedel-Craits type catalyst.If only one molecular equivalent of the ketene is reacted with thediketone, the iactone of a keto, beta-hydroxy carboxylic acid isproduced. When a second molecular equivalent of the ketene reacts withthe lactone of the keto-beta-hydroxy carboxylic acid, the lactone of abeta, beta'-dihydroxy, dicarboxylic acid is roduced. Generally underordinary conditions of operation a mixture results consisting of thelactone of th keto-betahydroxy carboxylic acid and the lactone of thebeta, beta'-dihydroxy dicarboxylic acid. These reactions may beillustrated by the followin equations:

wherein R1 and 3: each represent hydrogen; an alkyl group such asmethyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary andtertiary butyl, i. e., an alkyl group having the formula CnH2n+l where nis a positive integer from 1 to 4; an aryl group such as phenyl, 0-, m-,and p-tolyl. i. e., an aryl group of the benzene series having 8 to 10carbon atoms; and an aralkyl group such as benzyl, alpha and beta phenylethyl; R3 and R4 each represent an alkyl group such as methyl, ethyl.propyl, isopropyl, butyl, isobutyl, secondary and tertiary butyl, i. e.,an alkyl group of the formula C l-Irma where n is a positive integer of1 to 4 or an aryl group such as phenyl, 0-, m-, and p-tolyl, i. e., anaryl group of the benzene series having 6 to 10 carbon atoms; and m is apositive integer from 1 to 3.

The ketenes which may be employed in my process are represented by theformula:

wherein R1 and B: have the above designated definitions. I prefer to useketenes where R1 and R2 represent hydrogen or a methyl radical, i. e.,ketene or dimethyl ketene,

Diketones which may be employed have the formula:

0 a Rl "(CHl)n-l-Ri where R: and R4, and 11:. have the definitionsdesignated above. Typical diketones which may be used are diacetyl,acetyl acetone, propionyl acetone, butyryl acetone, valeryl acetone,acetonyl acetone, dibenzoyl, dibenzoyl methane. dibenzoyl ethane, andthe like.

The conditions under which the .ketene and diketone react may be variedaccording to the type of compounds used. Due to the inherent nature ofketenes to polymerize with ease, it is usually preferred to useconditions which are mild. The temperature may vary from as low sis-70C. to as high as +50 0. depending on the nature oi the reactants, typeof catalyst. and the absence or presence of a solvent. Generally atemperature of from about C. to 25 C. is preferred.

The catalyst employed is of the Friedel-Crafts type. For example, thehalides of boron, aluminum, zinc, iron, titanium, tin, and thelike maybe used. The amount of catalyst may vary from about 0.01 to 2% by weightbased on the amount of dlketone employed. Generally it is more practicalto use amounts varying from about 0.1% to 0.5% by weight based on theamount of the diketone. Boron trifluoride in the form of its etherate isthe referred catalyst since it permits a lower temperature to beemployed, thus eliminating the possibility of polymerization.

Solvents may or may not be used in my process, depending on the diketonewith which the ketene is condensed. Solvents which may be used arebenzene, toluene, xylene, heptane, dioxane, diethyl ether, isopropylether, carbon tetrachloride, carbon disulphide, ethylene dichloride, andthe like. If desired, a solution of lactone produced from a previous runmay be employed as solvent, thus obviating the necessity of removing asolvent from the neutralized reaction mixture. The lactone used as asolvent need not correspond to the lactone formed, it such-lactones maybe separated by flash fractional distillation under reduced pressures asis hereinafter described, or if the lactone mixture is to be used in thepreparation of synthetic resins, plastics, etc.

My process may be batch-wise or continuous, and if ketene has beenproduced by the pyrolysis of acetic acid, it may be advantageous tocarry out my reaction in a scrubber-type reactor. Such a process isdescribed in the co-pending application of Herbert G. Stone, SerialNumber 660,285, dated April 6, 1946. When a continuous process is to beused, any of the apparatus provided for such condensation-type reactionsmay be employed, The reaction chamber may or may not be packed with aninert packing such as Berl saddles, Raschig rings, etc. The flow ofreactants may he concurrent or counter-current, the lactone formed beingdrawn oil. as needed. When a The diolefin and continuous process is tobe employed, I prefer to utilize the apparatus described in thecopending application of Hugh J. Hagemeyer and Delmer C. Cooper, SerialNumber 660,286, filed April 6, 1946.

After neutralization of the crude reaction mixture, the resultingsolution is filtered, and a mixture consisting primarily of the reactionproducts of 1 mol of ketene with 1 mol of diketone and 2 mols of ketenewith 1 mol of diketone remains.

If desired the lactone mixture which results may be distilled into aflash iractionating column under high vacuum, and there separated intoits component parts. Since such a step requires such careful temperaturecontrol, it is usually preferred to use the mixture of lactones in thepreparation of other compounds which may be separated more easily. Forexample, the mixture of lactones may be distilled under atmosphericpresmixture of an oleilnic ketone and a diolefln being obtainedaccording to the equations:

' a. a a.

oleilnic ketone thus produced may then be separated easily by fractionaldistillation under reduced pressure, a polymerization inhibitor such ashydroquinone or beta-naphthol being used if desired.

Further possible uses for my lactone mixtures include hydrolyzing themixture to the corresponding beta-hydroxy carboxylic acids in thepresence of an acid catalyst, separating the mixture, or subsequentlydehydrating the hydroxy carboxylic acids to their correspondingunsaturated derivatives. This mixture of acids may then be separated bydistillation in a fractionating column under reduced pressures, etc.Also it is possible to treat my mixture of lactones with an alcohol toproduce a mixture of alkoxy acids, which may be separated easily byfractional distillation under a high vacuum. My lactone mixwe is alsosuitable for preparing unsaturated amides or nitriles.

The following examples are given to further characterize my invention.

- trample L-Reactioh of ketene with acetonul acetone and the dilactone:

is obtained. Some of the acetonyl acetone had cyclicized to 2,5-methyl,furan and in order to obtain a pure lactone mixture the solution waspassed into a chamber maintained at an elevated temperature underreduced pressure and equipped with a fractionating column. To furtheridentify the lactone mixture, the solution is heated un- .deratmospheric pressure at a temperature of 108 C. a vigorous evolution ofC0: taking place.

sure to induce decarboxylation of the lactones, a The residue wasfractionated and dfl yl (2,5-d1methyl-L5-hexadiene) B. P. 112 C... N1.4848,

having the formula CH: CH: -CH =JJ-CH|CHa( =CHi and 2-methylhexene-l-one 5 B. P. 154 C. at 734 mm. N 1.434s,

having the formula were obtained.

Example 2.-Reaction of ketene with. diacetyl and the dilactone:

on. on; 0=c-cn,con, :=o

is obtained. This mixture is then purified by flash fractionaldistillation under reduced pressure. In order to identify the lactonesformed, the mixture was subjected to decarboxylation at atmosphericpressure, and the residue or distillate subjected to fractionaldistillation. Twelve grams (12) of methyl isopropenyl ketone B. P. 95-98C. under 735 mm. having the formula:

and 2,3-dimethyl butadiene-l,3 (4 grams) B. P. 68 .C. under 735 mm.pressure and having the formula on; on.

H1C= =CH| are obtained.

Example 3.Reacttm o] ketene with acetul acetone Boron trlfluorideetherate (4 cc.) is dissolved in 300 cc. of acetyl acetone. Ketene isthen passed into the stirred solution which is maintained at atemperature of 0 C. by cooling. Ketene is passed in continuously until atotal or 4-5 mols has been added. The catalyst was then neutralized byaddition of an excess of sodium bicarbonate dissolved in several cos. ofwater, and the solution filtered. The excess or unreaeted acetyl acetonewas removed by flash distillation in a fractionating column maintainedunder reduced ressure, and a mixture of the mono lactone:

and the dllactone:

CH| CHI o=coH.h-cm -cn,o=o

is obtained. In order to identify these lactones. the mixture isdistilled under atmospheric pressure at a temperature of -110 C., avigorous evolution of CO: taking place. In order to completelydecarboxylate any lactone, the mixture is distilled under total refluxfor one hour, at the end of which time the mixture is fractionallydistilled, 22 gms. of diisopropenyl methane B. P. 88 C. at 735 mm. N1.4399

having theformula:

and 47 grams of 2-methyl penten-1-one-4, B. P. 127' under 735 mm., N1.4412

having the formula:

2 C i" CHzb-CH:C=C H:

are obtained.

Example 4.Reaction of ketene with dibenzoyl methane 112 grams ofdibenzoyl methane are dissolved in a 0.5% solution of boron trifluorldeetherate in one liter of diisopropyl ether. The solution is cooled to10-20 C. and a half mol of ketene is passed in through a high speedstirrer. Solid anhydrous sodium acetate is added to neutralize thecatalyst and the solution is filtered. The solvent is removed at reducedpressure leaving a mixture of dibenzoyl methane and the correspondingmonoand di-lactones. Decarboxylation was accomplished by heating theresidue at -150 C. 14.7 liters of CO: were evolved which indicates aconversion of 65 per cent based on the ketene.

Similarly when dibenzoyl is reacted with ketene a mixture of lactoneshaving the formulae:

acted with ketene a mixture of lactones having 7 the formulae:

is obtained.

What I claim as my invention and desire to be protected by LettersPatent of the United States is:

1. A process for preparing beta-lactones which comprises reacting at atemperature of -70 C. to 50 C. a ketene having the formula:

and

X B: I wherein R1 and R: each .represents a member selected from thegroup consisting of a hydrogen atom, a methyl group. an ethyl group, anda phenyl (CsHs-) group, with a diketone havin the formula: 4

wherein Rs and R. each represents a member selected from the groupconsisting of alkyl groups of the formula CnHrnH wherein n is a positiveinteger from 1 to 4, and a phenyl (C8H5-) group, and m is a positiveinteger from 1 to 3, in the presence of a Friedei-Crafts catalyst.

2. A process for preparing beta-lactones which comprises reacting'at atemperature of -I C. to 50' C. a ketene having the formula:

wherein R1 and R: each represents a member selected from the groupconsisting-of a hydrogen atom. a methyl group, an ethyl group, and aphenyl (CaHs) group, with adiketone having the formula:

wherein R; and R4 each represents a member selected from the groupconsisting of alkyl groups of the formula CnH2n+l wherein n is apositive integer from 1 to 4, and a phenyl (CsHs-) group, and m is apositive integer from 1 to 3, in the presence of a Friedel-Crafts catalyst, and in the presence of an inert solvent.

3. A process for preparing beta-lactones which comprises reacting at atemperature of -'I0 C. to 50 C. a ketene having the formula:

wherein R1 and R: each represents a member selected from the groupconsisting of a hydrogen atom, a methyl group, an ethyl group, and aphenyl (0035-) group, with a dlketone having the formula: a a

0 O 38-15 (C H5) g-RI wherein R: and Rs each represents a memberselected from the group consisting of alkyl groups of the formula CnHsaHwherein n is a positive integer from 1 to 4, and a phenyl (C'sHs-)grain. and m is a positive integer from 1 to 8. in the presence of from0.01% to 2% by weight. based on the diketone, of a Frledel-Craftscatalyst.

4. A process for preparing beta-lactones which comprises reacting, at atemperature of -'I0 C. to 50 C., ketene (CH.2=C=O) with a diketonehaving the formula:

wherein R3 and R4 each represents a member selected from the groupconsisting of alkyl groups of the formula CnH2h+l wherein n is apositive integer from 1 to 4, and a phenyl (CsHo-) group,

and m is a positive integer from 1 to 3, in the presence of from 0.01%to 2% by weight, based on the diketone, of a Friedel-Crafts catalyst.

6. A process for preparing beta-lactones which comprises reacting at atemperature of -7ll C.

to 50 C. a ketene having the formula:

c=c=o R,

wherein R1 and R2 each represents a member selected from the groupconsisting of a hydrogen atom, a methyl group, an ethyl group, and aphenyl (CsI-l's) group, with a diketone having the formula:

0 g H R:- (CHr) i-C-Rs wherein R3 and R4 each represents an alkyl groupof the formula CaHzn-H wherein n is a positive integer from 1 to 4. andm is a positive integer from 1 to 3, in the presence of a Friedel-Craftscatalyst.

'7. A process for preparing beta-lactones which comprises reacting at atemperature of 'l0 C. to 50 C. a ketene having the formula wherein R1and R2 each represents a memberselected from the group consisting of ahydrogen atom, a methyl group, an ethyl group, and aphenyl (CsHs) group,with a diketone having the formula:

o RI-A(CH2)w-l -R| wherein R and R4 each represents an alkyl groupphenyl (CsHs-) group, with a diketone havin the formula:

wherein 122 represents an integer from -1 to 3, in the presence of aFriedel-Crafts catalyst.

9. A process for preparing beta-lactones which comprises reacting at atemperature of 70' C. to 50 C. a ketene having the formula:

c=c=o Rs wherein R1 and R: each represents a member selected from thegroup consisting of a hydrogen atom, a methyl group, an ethyl group, anda phenyl (CsHc-) group, with a diketone having the formula:

wherein m represents an integer from 1 to 3, in the presence of from0.01% to 2% by weight, based on the diketone. of a Friedel-Craftscatalyst.

10. A process for preparing beta-lactones which comprises reacting, at atemperature of 70 C. to 50 C., ketene (CH:=C=O) with a diketone havingthe formula:

wherein R: and R4 each represents an alkyl group of the formula CnH2n+1wherein n is a positive integer from 1 to 4, and m is a positive integerfrom 1 to 3, in the presence of a Friedel-Craits catalyst.

11. A process for preparing beta-lactones which comprises reacting, at atemperature of 70 C. to 50 C., ketene (CH:=C=O) with a diketone havingthe formula:

wherein Ra and R4 each represents an alkyl group of the formula CnH2n+iwherein n is a positive integer from 1 to 4, and m is a positive integerfrom 1 to 3, in the presence of from 0.01% to 2% by weight, based on thediketone, of a Friedel- Crafts catalyst.

12. A process for preparing beta-lactones which comprises reacting, at atemperature of C. to 50 0., ketene (CI-Ia=C=O) with a diketone havingthe formula:

iana-E0 wherein m represents an integer from 1 to 3, in the presence ofa Friedel-Crafts catalyst.

13. A process for preparing beta-lactones which comprises reacting, at atemperature of 'l0 C. to 50 C.. ketene (CH2.=C=O) with a diketone havingthe formula:

wherein mrepresents an integer from 1 to 3, in the presence of from0.01% to 2% by weight, based on the diketone, in the presence of aFriedel-Crafts catalyst.

14. A process for preparing a mixture of a mono-lactone having theformula:

0 CH; ORA-C Bali-C HsO=O and a dilactone having the formula:

on. cm o-c-cma-cmcmc=o which comprises reacting at a temperature from-'l0 C. to +50 C. gaseous ketene with a solution containing aFriedel-Crafts catalyst dissolved in acetyl acetone.

15. A process according to claim 14 wherein 0.1% to 0.5% by weight ofcatalyst based on the acetyl acetone is used and a temperature of 10 C.to 25 C. is maintained.

16. A process for making a mixture of a monolactone having the formula:

and a dilactone having the formula:

cm on. o-c-cn.J:--J:-omc=o which comprises reacting at a temperaturefrom -'!0 C. to +50 C. gaseous ketene with a solution containing aFriedel-Crafts catalyst dissolved in diacetyl.

17. A process according to claim 16 wherein an amount of catalyst from0.1% to 0.5% by weight based on the diacetyl is used at a temperaturefrom 10 C. to 25 C.

18. A process for preparing a mixture of a betalactone having theformula:

and a dilactone having the formula:

CH: CH: o=c-cH.c-cmcrnc=o which comprises passing gaseous ketene into avigorously stirred solution of 0.1% to 0.5% by weight based on theacetyl acetone of boron fluoride etherate dissolved in said acetylacetone,

continuing the passage of ketene into the solu-- tion untilsubstantially all the acetyl acetone has reacted while maintaining thetemperature from -l0 C. to +50 C., neutralizing the catalyst with aweal: alkaline solution. and thereafter separating the mixture oflactones from the unreacted residue.

. '11 1 g .12 19. Aprocessior preperingemixture oiarnono 21. A processaccording to claim '20 wherein lactone having the formula: g 0.1% to0.5% by weight of catalyst. based on the Y o dibenzoyl methane is usedand a temperature of C. to C. is maintained.

-Q W g 22. A process for preparing a mixture of mono lactone having thefornmla: and a dilactone having the formula: g o o.

cm cm OE-cm-L'cm-E-o which comprises passing keteneinto a vigorouslystirred solution containing diacetrl in which has been dissolved 0.1% to0.8% by weight based on and a dilactone having the formula: the diacetyioi boron fluoride etherete. contino o uingpassage of the keteneintothesolutionimtil substantially all the diacetyi has reacted whilemaintaining the temperature from 'l0' 0. to s I +50 0., thereafterneutralising the catalyst with a solution of a weak alkali. andseparating the '20 1 lactone mixture from the residue.

20.Aprpcessforpreparingamixtureofa 4 fin Y which comprises passinggaseous ketene into a mono. Mme the 10mm" vigorously stirred solution ofdibenzoyl methane having dissolved therein from 0.1% to 0.5% by weight,based on the dibenzoyl methane, of heron trifiuoride etherate.continuing the passage of the o ketene into the solution untilsubstantiallyall the OQ 433F080 dibenzoyl methane has reacted whilemaintaina Z a ing the temperature at from -'l0 C. to +50 0..

thereaiter neutralizing the catalyst with a soluand a dilactone havingthe formula: tion of a weak alkali, and separating the lactone v mixturefrom the residue.

. 85. HUGHJ. HAGMYER, Ja.

' REFERENCES CITED The following references are of record in the file ofthis patent:

' UNITED s'ra'rns PATENTS which comprises reacting at a temperature of40 -70? C. to C. gaseous ketene with a solution Number Nme Duecontaining a Friedel-Crafts catalyst dissolved in KW W- 22, 1944dibenzoyl methane.

